The present invention relates to a mechanism for opening/closing a toner falling aperture through which toner is supplied from a toner cartridge to the developing device in an image forming apparatus such as an electrostatic copying apparatus, a facsimile, a laser beam printer or the like.
In the image forming apparatus above-mentioned, a toner cartridge is removably attached to a housing concave in the main body of the image forming apparatus. A toner cartridge of which toner has been used up, is to be replaced with a new toner cartridge.
Generally, a toner cartridge has a sealing member made of an elastic sheet which removably covers, at the outer surface of the main body of the toner cartridge, a toner falling aperture formed in the bottom of the toner cartridge main body in which toner is housed. After the toner cartridge has been set to the housing concave, the sealing member is torn off, causing the toner falling aperture to be opened. Then, toner falling through the toner falling aperture, is supplied to the developing device which is disposed under the toner falling aperture. The sealing member thus torn off, is separated from the toner cartridge and taken out to the outside of the main body of the image forming apparatus. This disadvantagesouly presents the problem that the toner stuck to the sealing member scatters inside and outside of the main body of the image forming apparatus.
On the other hand, there is proposed an image forming apparatus having an opening/closing mechanism for opening/closing a toner falling aperture formed in the bottom of the main body of a toner cartridge. Further, the developing device may be made in the form of a unit and adapted to be inserted in and removed from a housing concave of the main body of an image forming apparatus. In this connection, there is proposed an image forming apparatus having an opening/closing mechanism for opening/closing a toner falling aperture formed in the top surface of the developing unit.
Conventionally, the opening/closing mechanism of the developing unit is operated irrespectively of the operation of the opening/closing mechanism of the toner cartridge. This produces a difference in toner falling aperture opening/closing timing between the opening/closing mechanisms. This may cause toner to fall in the space between the opposite surfaces of the developing unit and the toner cartridge (between the top surface of the developing unit and the underside of the toner cartridge). This involves the likelihood that the falling toner scatters at the time when the toner cartridge is pulled out.